Diffraction and interference

Two waves E and G are shown. The waves have the same speed.

Which statement is correct?

• Wave E has a greater amplitude than wave G.

• Wave E has a greater intensity than wave G.

• Wave E has a smaller frequency than wave G.

• Wave E has a smaller wavelength than wave G.

The diagram shows a displacement-time graph for a progressive wave.

• Amplitude: 5 mm; Frequency: 40 Hz

• Amplitude: 5 mm; Frequency: 50 Hz

• Amplitude: 10 mm; Frequency: 40 Hz

• Amplitude: 10 mm; Frequency: 50 Hz

Which observation indicates that sound waves are longitudinal?

• Sound can be reflected from a solid surface.

• Sound cannot be polarised.

• Sound is diffracted around corners.

• Sound is refracted as it passes from hot air to cold air.

A diffraction grating is used to measure the wavelength of monochromatic light, as shown in the diagram.

The spacing of the slits in the grating is 1.00 x10^-6 m. The angle between the first order diffraction maxima is 70.0^o.

What is the wavelength of the light?

• 287 nm

• 470 nm

• 574 nm

• 940 nm

Interference of light is evidence that:

• the speed of light is very large

• light is a transverse wave

• light is electromagnetic in character

• light is a wave phenomenon

In a Young's double-slit experiment the centre of a bright fringe occurs wherever waves from the slits differ in the distance they travel by a multiple of:

• quarter of a wavelength.

• half a wavelength.

• a wavelength.

• three-fourths of a wavelength.

In a Young's double-slit experiment, the slit separation is doubled. To maintain the same fringe spacing on the screen, the screen-to-slit distance D must be changed to:

• D/2

• D $\sqrt{2}$

• 2D

• 4D

For destructive interference, the path difference is:

• odd number of half wavelengths

• even number of half wavelengths

• whole number of wavelengths

• even whole number of wavelengths

Constructive interference happens when two waves are:

• out of phase.

• zero amplitude.

• in phase.

Two waves with phase difference 180° have resultant of amplitude

• one.

• zero.

• same as the single wave.

• doubles the single wave.